12 Researches respecting the 



parenchvmc of the leaf, and thus retain the utriculae con- 

 jugate or conjoined. 



To enable the reader to comprehend better what is here 

 said, I shall refer to fig. 1, which represents a portion of the . 

 leaf of the fritillaria with the pelhcle removed at B. It 

 will first be observed that the leaf is greener in that part; 

 that the lateral surfaces of the exterior utriculae remain ad- 

 hering to the parenchynie, and that they retain the utriculae 

 conjoined, in the centre of which the pore is seen. 



Fig. 2 exhibits this pellicle removed, and pierced with as 

 many oval apertures as there were conjugate utriculce in the 

 leaf. 



The size of these apertures clearly proves that, besides 

 the pore, a part of the conjugate utriculje rerrtains exposed to 

 tlie air, which thus concurs with the exterior utriculs; to 

 the formation of the surface of the leaf. Fig. 5 and 6 give 

 a pretty correct idea of the manner in which the conjugate 

 utriculae are enveloped by the exterior utriculae, and of the 

 part of these utriculae which remains uncovered. 



The apertures here mentioned are not of the same form 

 in the diifercnt plants: in the fritillaria they are always 

 oval, while in the aloe they are square, fig. 13, which I can 

 ascribe only to the form of the exterior utriculae, which 

 are elongated in the fritillaria and hexagon in the aloe. 



The conpigate utriculae are not united to the parenchyme 

 by their lower part, as the exterior utricu!^ are ; below them 

 is found a vacuity, as seen fig. 7, vvhich communicates ou 

 one side with the pore, and on the other with the utricular 

 intoslices, which 1 shall speak of in describing the paren- 

 ch\ane. This vacuity is very remarkable in the leaf of the 

 aloe, both on accoun{ of its size and its funnel-like appear- 

 ance. 



Tl>e conjugate utricular are filled with a juice which seems 

 to be of the same nature as that of the utriculae of the par- 

 encbyme; in general it is green and sometimes transparent. 

 It often contams a great number of small globules, which 

 render these utricuke opake : but if the utriculae be slightly 

 compressed, all these globules unite as several globules of 

 oil would do, and thus communicate to the utriculae a part 

 of their transparency. 



Ever>' time I observed the pores with the microscope, 

 taking care to moisten the pellicle, they always appeared to 

 ine to be ahnost always filled with a black matter, fig. 1 and 

 14, which is nothing else than a small bubble of air retained 

 there, and which 1 was enabled to detach by slightly com- 



presjiag 



